Child secondhand smoke exposure (SHSe) is a significant, complex public health problem that is linked to cancer and cardiovascular disease risk factors, and many other health consequences including asthma, otitis, SIDS, and dental carries. With many regions adopting public smoking bans, reducing home-level smoking (homes and cars) has become the last bastion of intervention to protect children from SHSe. In addition, reducing SHSe in low-income, medically-underserved communities has become a public health priority due to the increased SHSe morbidity burden these populations bear. Given evidence that single-level approaches (e.g., home smoking bans brief provider advice) are insufficient to tackle the many facets of this multi- determined problem, this proposal will test a comprehensive, multilevel intervention in communities with the highest SHSe morbidity risks. The proposed intervention model integrates strategies across clinic, family, and community levels of service. While specific components are evidence-based, the proposed model is novel and consistent with the NIH roadmap to advance the science of behavior change by testing multilevel interventions. We propose to provide a clinic-level quality improvement (CQI) intervention based on Clinical Effort Against Secondhand Smoke Exposure (CEASE) to address child SHSe in 4 pediatric clinics in low-income Philadelphia communities. We will then randomize 466 eligible smoking parents visiting these clinics into a home-level behavioral counseling intervention (CQI+BC) based on Family Rules for Establishing Smoke-free Homes (FRESH), or a home-level attention control intervention (CQI+A). CQI+BC merges behavioral counseling (e.g., intensive skills training, support) where SHSe occurs (home/car) with navigation of community-level services to facilitate access to and effective use of no-cost nicotine withdrawal medications. Participants will complete assessments at pre-treatment, 3-month end of treatment, and 12-month follow-up. The primary aim is to test the hypothesis that relative to CQI+A, CQI+BC will result in greater reductions in child cotinine (SHSe biomarker) and reported cigarettes exposed/day. A secondary aim is to test the hypothesis that relative to CQI+A, CQI+BC will result in a higher cotinine-verified, 7-day point prevalence quit rate among parents. We also will test the hypothesis that social support, coping skills, and self-efficacy mediate effects of CQI+BC on smoking outcomes and explore whether other smokers at home, level of nicotine dependence, and depression/anxiety symptoms attenuate treatment effects. The proposed approach is likely to be more effective than existing, single-level approaches because the integrated intervention levels reinforce one another, potentially producing synergistic effects on outcomes. In addition to improving patient care, this model has high potential for dissemination and public health impact by reducing tobacco-related health and cost burdens in target populations that would benefit most from this approach. Findings from mediator and moderator aims will inform theory and future directions in this field by identifying how and for whom the intervention works.